TM10-4320-226-141.14.2 Unit Maintenance Functional Description.1.14.2.1ExhaustSystem. The exhaust system consists of the muffler, exhaust tubing and spark arrester. Themuffler is connected directly to the engine and provides a noise reduction. Exhaust tubing provides an enclosed path forthe released gases from the muffler to the spark arrester.The spark arrester prevents sparks from entering theatmosphere and rain from entering the exhaust.1.14.2.2AirCleaner. The air cleaner provides filtered air to the combustion chamber of the engine. It consists of twofilters that filter the air before it reaches the intake manifold of the engine.1.14.2.3Electrical System (Except Model 350 PAWN). The electrical system (figure 1-3) provides the electrical control circuits and 12 V dc. Two 12 volt batteries are connected in parallel. The batteries supply the initial starting power.The electrical wiring harness connects the electrical components of the control panel and engine. WhenEMERGENCY-STOP (OFF-ON) switch (S1) is pulled out, S1 contacts connect ammeter (Ml), START switch (S2) andswitch (S4) to positive side of battery. When cooling fan blower belt is installed on engine, S4 contacts 4 and 2 are closed,connecting OIL PRESSURE BY BASS switch (S3) to positive side of battery. When S3 is pressed, relay (K2) is energizedand normally open contacts of K2 are closed.Since the contacts of K2 are closed, 12 V dc is applied to fuel shutoffsolenoid (L1). L1 then connects ground to K1 via auxiliary tap (AUX) and K1 energizes. Mechanical linkage is connectedfrom L1 to the cut-off lever that controls fuel flow into engine. Since L1 retracted, fuel can be injected into engine andK1 is energized. When K1 is energized, normally open contacts 6 and 8 are closed. Since S2 is pressed, 12 V dc is appliedto starter relay (K3). K3 energizes and provides 12 V dc to starter motor (B1). This causes drive gear of B1 to engagewith engine flywheel and causes B1 to rotate. Rotation of B1 cranks engine until S2 is released. After starting, S2 isreleased and 12 V dc is removed from K3. Since no voltage is applied to K3, 12Vdc is removed from B1. When B1 hasno voltage, drive gear of B1 is disengaged from engine and B1 no longer rotates. When oil pressure reaches 4 psi (27.579kPa), oil pressure switch (S5) closes and S3 is now released. The 12 V dc is till applied to K2 via closed contacts 1 and3 of K1, which keeps L1 retracted. Alternator (G1) is turned by engine drive pulley and outputs approximately 14V. The14V then provides 12 V dc to keep K1 and K2 energized. In addition, 14 V from G1 recharges 12 V dc batteries.Since the engine can be damaged by overheating, V-belt switch (S4) is provided. If the V-belt that turns the cooling fanbreaks, S4 opens, When S4 is open, 12 V dc is removed from K1 and K2. This causes L1 to extend (fuel closed) andshuts off fuel flow to engine. Since no fuel is provided to engine the 350 GPM pumping assembly is stoppedSince oil provides both lubrication and cooling to the engine, an oil pressure switch (S5) is provided. If engine oil pressuredrops below 4 psi (227.579 kPa), S5 opens. WhenS5 is open, 112 V dc for K1 and K2 is removed. This causes L1 to extend(fuel closed) and shuts off fuel flow to engine. Since no fuel is provided to engine the 350 GPM pumping assembly stops.When operation is no longer required, S1 is pushed in and 12 V dc is removed from K1 and K2. This causes L1 to extend(fuel closed) and shuts off fuel flow to the engine. Since no fuel is provided to the engine, 350 GPM pumping assemblystops. When an emergency occurs, S1, the emergency stop switch provides rapid engine shut down. Pull position isnormal operation, push position is shutdown,Change2 1-11
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business
